Figure 8.

Light Sensitivity of Synechocystis and Arabidopsis Wild-Type and Mutant Strains.

(A) Light sensitivity of Synechocystis 6803 wild-type and Δpsb29 cultures measured as the ratio of F_v/F_m values after treatment with high light intensities for 20 min followed by 7 min dark adaptation to F_v/F_m values before the treatment. F_m values were determined by a single high intensity light flash. Starting F_v/F_m values were in the range of 0.35 ± 0.003 and 0.29 ± 0.03 for wild-type and Δpsb29 cells, respectively. Error bars represent sd based on mean values of two replicate cultures.

(B) Light sensitivity of Arabidopsis wild-type and M2-6 plants calculated as the residual F_v/F_m value after exposure to high light intensities for 15 min, followed by 7 min dark adaptation. Starting F_v/F_m values were in the range of 0.8 ± 0.01 and 0.79 ± 0.02 for wild-type and M2-6 plants, respectively. The experiment was performed under five different light intensities using different wild-type and M2-6 plants for each light treatment. The data between 1500 to 4000 μmol photons m⁻² s⁻¹ were fitted by linear regression, resulting in slope coefficients of −4.3E-5 ± 3.7E-6 for the wild type and −8.9E-5 ± 7.4E-6 for M2-6 plants. These values are significantly different at P < 0.01 based on a two-sample, two-tailed Student's t test.

(C) Growth of wild-type Columbia-I and M2-6 mutant plants under normal (NL; 50 μmol photons m⁻² s⁻¹) or low (LL; 10 μmol photons m⁻² s⁻¹) growth light conditions.